Energy storage technologies are a strategic and necessary component for the efficient utilization of renewable energy sources and energy conservation. There is a great technical potential to substitute for burning fossil fuels by using stored heat that would otherwise be wasted and using renewable generation resources. These energy sources can be used more effectively through the addition of short- and long-term energy storage. Thermal and electrical energy storage systems enable greater and more efficient use of these fluctuating energy sources by matching the energy supply with demand. Thermal energy storage can also be used for cooling to reduce or eliminate the demand for electricity, including the most expensive electrical energy that is generated during periods of peak power demand. The overall objective of the Implementing Agreement on Energy Conservation through Energy Storage is to develop and demonstrate various advanced energy storage technologies for application within a variety of energy systems, and to and encourage their use as standard engineering design options. The balance of activities focuses on case studies, demonstrations, deployment measures and design tools. The work programme includes a range of tasks relating to development of underground thermal energy storage systems in the buildings, industrial and agriculture sectors; examination of the potential role of electrical storage technologies in optimising electricity supply and use; examination of the role of phase-change materials and thermo-chemical reactions in energy systems; and development of procedures and screening and decision tools to facilitate the adoption of energy storage in project designs. Most of this activity is undertaken through task-shared projects although some cost-shared work is also undertaken. Work conducted under the programme has influenced many large projects. Several plants using direct cooling and cold storage were built or are under construction in participating countries as a result of programme activities.

18. Transportation of Thermal Energy Utilizing Thermal Energy Storage Technology
The general objectives of this Annex 18 on Transportation of Energy by Utilization of Thermal Energy Storage Technology are to identify state-of-the-art for using different technologies for energy storage and transportation, to broaden and co-ordinate the knowledge within the field, and to disseminate information. This is done through targeted R&Defforts.

19. Optimised Industrial Process Heat and Power Generation with Thermal Energ
The general objectives of the proposed Annex are to overcome the fragmented research and to achieve synergies from existing and new future HTTES activities. The objectives of the work to be performed under this Annex are: • To conduct a general review and assessment study of existing and emerging HTTES technologies • To identify obstacles that need to be overcome to make industrial process heat and power generation with TES more economically and environmentally viable • To identify efficient and economic storage materials • To compare and assess different HTTES concepts and design • To define strategies for efficient storage integration and operation • Technology transfer

20. Sustainable Cooling with Thermal Energy Storage
The general objectives of the proposed annex on Transportation of Energy by Utilization of Thermal Energy Storage Technology are to identify state-of-the-art for using different technologies for energy storage and transportation, to broaden and coordinate the knowledge within the field, and to disseminate information. In particular, research on high capacity storage materials and high thermal power charging and discharging technologies that are easy to implement in an energy transport system will be encouraged, along with research on system aspects where heat sources are linked to the customer’s need and where these links’ impact on system design is assessed. Potential cost-effective applications must be identified. At the end of the annex, present activities within the field are expected to be better coordinated, and initiatives for new activities have been taken.

21. Thermal Response Test for Underground Thermal Energy Storages
The overall objectives of Annex 21 are to compile TRT experiences worldwide in order to identify problems, carry out further development, disseminate gained knowledge, and promote the technology. Based on the overview, a TRT State of the art, new developments and further work are studied.